Well, what do you all think?

[Jesse Lackman]

Are all the bends going to pollute the signal?

I do plan on using Bruce's flow straighteners at strategic locations in the piping as soon as he has them for sale.

:;):

More at the update link in the pitot section of the board.

[SuperRunner]

Looks nice.
lets see a close up on your air valves. I am thinking of re-doing mine.

[Jesse Lackman]

Background information;



There is a better valve arrangement, someone here made valves out of a sliding pipe within a pipe, very nice.

Here's the thread;

[Mouse]

Looking good!

What did you have to do to convert a Merdog bench to Pitot?

[Jesse Lackman]

All I really had to do was;

leave out the orifice disk mounting board,

install a test fixture feed box in the valve chamber,

connect the valve chamber to the test fixture feed box with the piping you see in the picture above.

How about a couple pictures of bi-directional averaging elliptical pitot tube construction?




I'm going to pull the wood out, it is holding the small high pressure signal tubes in place while the JB dries. When the wood is out I have another tube that will be positioned in the middle for the static signal. The open cavity will be potted with epoxy of some sort to seal the tubes from each other. I hope those high pressure signal tubes are big enough.

I'm making two identical units like this. I'm thinking about installing them 90 degrees from each other.

I stewed over these pitots for a long time, hashed it all night long last night, it turned out to be nothing complicated at all.

:p

[larrycavan]

The bench is looking good Jesse. I have to say though...sure looks like a lot more work than an orifice bench...

My special order Dwyer pitot came today. .120" diameter tubing, custome J bend, 12" reach...under $100..

[Jesse Lackman]

That pitot must be for velocity probing a port right?

The biggest problem is that you have to be a contortionist to bolt up the 4" flange under the test fixture feed box.

Hopefully I can make up some work and headache in the tuning and calibration phase. I saw on speedtalk where you said to study and understand how manometers work, I see all this complicated stuff on orifice plate CDs etc, well I don't know if I want to overload my poor brain with that stuff so I'm simply blowing it all off with the FP-1 and a pitot. Orifices are for round robins. :laugh:

Even Einstein didn't know his own phone number, he said why clutter up your brain with something you can look up in a book.

The pitots are done except for the impact and static holes, now it is deciding the hole size and on which duct traversing gobbledy-gook to use, "Centroids of Equal Areas" or "Log-Tchebycheff"

I think the pitots might be better with the signal tubing sticking out both ends that way one could tee both ends to the FP-1 ports. That might offer a better signal than coming off of only one end of the pressure signal tubes.

BTW I'm getting a quote on custom tube in a 4:1 ellipse .875 x .218. If it is reasonable I might by some.

[Jesse Lackman]

I ruined one of my pitots last night trying to drill the "Centroids of Equal Areas" impact ports. Some of the ports didn't end up perfectly on the leading edge of the ellipse. I had a fixture made out of MDS and metal but those small drill bits wander, it migh have worked better if the drill guide I made was right on the pitot leading edge instead of 1/2 inch (through MDS) away.

It will probably have to be done on a milling machine or maybe I could use a center cutting end mill in my drill press.

[Jesse Lackman]

Something just clicked! Gotta plan now!

Good thing I didn't throw the drill guide against the wall in my frustration.

:p

[larrycavan]

Just pickin at ya with the "orifice bench" comment Jesse....

[Jesse Lackman]

I just did a down and dirty test of the screwed up pitot to see how bi-directional it will be. I have it mounted in a 3" pipe, have a shop vac hooked up, and used the 100cfm orifice plate I got from Bruce.

The pitot showed 101.3 installed one way and 101.6 installed the other way.

The pitot actually works.

It looks like these pitots will be bi-directional without any huge calibration change.